Chilling roll for paper coating machines



Jim 6, 1959 J. D. MALONEY, JR.. ET AL 2,867,414

CHILLING ROLL FOR PAPER COATING MACHINES Filed Dec. 23. 1955 2sheets-snee: 1

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5N m t i l s www s @N Neg E Jan. 6, 1959 J. D. MALONEY, JR., ETAL2,8@7414 CHILLING ROLL FOR PAPER comme MACHINES 2 Sheets-Sheet 2 FiledDec. 25. 1955 CHILLING ROLL FOR PAPER COATING MACHINES James D. Maloney,Jr., Kingston, hio, and Clinton B.

Brown, Staatsburg, N. Y., assignors to The Mead Corporation, Dayton,Ohio, a corporation of Ohio Application December 23, 1955, Serial No.555,061

1 Claim. (Cl. 257-95) The present invention relates to a chilling rollfor paper coating machines and particularly to a chilling roll for usein a paper coating machine such as that described in Patent No.2,647,842, issued August 4, 1953 to R. N. Griesheimer and Robert C.Hydell.

l-leretofore, the design of rolls for heat transfer (heating orcooling)has centered mainly around drier drums and calender rolls. In the caseof drier drums, there is little or no nip loading, while calender rollscarry nip loads in the range of 100G-1500 lb. per inch of roll face. Onthe other hand, nip loading on the chilling roll of this inventionamounts to 150-200 lb. per inch of face. This difference in loading isan important distinction because it affects the structure of the roll.The heavier structure required by the higher nip loadings makes itditiicult to accomplish good heat transfer because of the thicksections. The intermediate to low loading imposed on the roll of thisinvention is`carried by an inner core, thus allowing the outer shell tobe relatively thin.

Another requirement imposed by the process of Patent No. 2,647,842 isthat the inter-nip distance between the coating application press andthe press of which the present roll is a part must be held to a minimum.To meet this requirement, a roll of relatively small diameter isnecessary; in fact, the smaller, the better, as long as its design isconsistent with load and heat transfer requirements. For this reason,theadvances in drier design have limited application, as it is almostimpossible to provide the internal connections of the substantiallylarge diameter driers in a roll of relatively small diameter.

Roll surface temperature is also of importance. Since it costs much moreto transfer heat at low temperature Q/0 is the rate of heat transfer inheat units per unit time, such as B. t. u./hr.,

H is the overall heat transfer coefficient,

A is the area of roll surface through which the heat is transferred, and

AT is the temperature diierence between the outer surface of the rolland the cooling medium within the roll.

The numerical value of heat transfer rate, Q/ 0 that is required is setby the production requirements imposed on the coating machine. Thus, fora given coate'r. operating at its rated capacity, the value of Q/ 0 isfixed, and the chill roll must be so designed to yield this rate of heattransfer.

2,867,4ii Patented Jan. 6, 1959 The area available for heat transfer isrelated, among other factors, to the diameter of the chill roll, afactor limited by the space requirements of the coating process, asdiscussed above.

The cost of transferring heat at temperatures of the order of 50 F. ishigh, and dictates a design giving a minimum difference between rollsurface and cooling medium. Hence, desirably, AT in the above equationis small.

This leaves the factor H, overall heat transfer coeilicient, as the onlymeans of attaining the desired rate, Q/H, and H must be made as large aspossible. To insure a high value of H, a relatively high velocity of thecooling medium, over the inside surface of the roll shell is required.

This requirement, as well as the others set forth above, is met by thechill roll of this invention.

Generally, in accordance with the present invention, there is provided achilling roll consisting of an elongated inner cylinder of substantialthickness in the outer face of which is provided a plurality of spacedhelical grooves. Sweated over the inner cylinder is a relatively thinshell which acts to close the outer portions of the grooves to therebyform passages between the inner cylinder and its shell. Alternategrooves at one end of the device communicate with radially drilled holeswhich. in turn, communicate with an annular space dened by a cover plateset within a recess and by anges extending outwardly from an inner pipe.There is also provided an outer pipe and the remaining groovescommunicate with the space between the inner and outer pipes and theaforesaid flange by means of milled openings in internal flanges of theinner roll. The device is such that brine such as, for example,methylene chloride brine at very low temperatures may be introducedsimultaneously through both of the inner pipes whereupon the same maypass through the radial openings, thence through the communicatinggrooves to the milled passages at the opposite side of the device andthence through the space between the inner and outer pipes. Such actionmakes for a minimum heat transfer film coefficient for the brine as itpasses through the grooves, it being understood that the llow of brinethrough the grooves is at high velocity and is in opposite directions inalternate grooves. Thus, also, the chilling surface, namely the outersurface of the shell, will have a more uniform temperature at all timesthan would otherwise be possible. The device contains many novelfeatures .which will be brought out in the appended specification.

It is accordingly an object of the invention to provide a novel chillingroll especially adapted for use with paper coating machines.

Another object of the invention is to provide, in a device of thecharacter set forth, a novel arrangement' l of grooves whereby the nipbetween the instant device and a roll with which it may be utilized maynot ride a particular groove.

Another object' of the invention is to provide a device of the characterset forth which is simple in construction, inexpensive to manufactureand yet effective and efficient in use.

Still another object of the invention is to provide, in a device of thecharacter set forth, a plurality of brineconducting grooves arranged ina roll in other than circumferential relationship therein in spacedrelation to one another and with novel means whereby brine is directedin opposite directions therethrough in successive grooves.

Other and further objects of the invention will become .apparent from areading of the following specification taken in conjunction with thedrawings, in which; l

Figure 1 is an elevational view of an embodiment of the invention,

Figure 2 is an end elevational view thereof,

Figure 3 is an enlarged fragmentary sectional view, partly broken away,taken along line 3-3 of Figure 1,

Figure 4 is a sectional view taken along line 4 4 of Figure 3, and

Figure 5 is a view similar to Figure 3 but illustrating diagrammaticallythe direction of tiow of lluid through the device embodying the presentinvention.

Referring more particularly to the drawings, there is and has at itsinner end an integrally formed outwardly v extending flange 17 which isaixed to, in each case, to one end of the roll 10 by means of bolts 18.

The flange l1 is further recessed at each of its ends, as indicated at19 and a cover plate is aliixed in each of the recesses by means ofbolts 21. The cover plate is indicated at 20. An outer pipe 22 isatlixed within each of' the fittings 16.

In the outer face of the roll 10 is cut a plurality of vspirallyextending shallow grooves 23 which lie in spaced parallel relation toone another. Adjacent one end of the roll 10 each alternate groove 23has communicating l therewith a radially extending drilled hole 24. Inthe opposite end of the roll those grooves having the drilled hole inone end communicate with a radially extending milled groove 25.

Shrunk or sweated over the roll 10 is a shell 26, preferably of steeland in the form of a seamless pipe. The

outer surface of the shell 26 is preferably chromium plated andpolished.

In the operation of the present form of the invention, brine, such asmethylene chloride brine at a very low temperature, is introduced intothe device through both inner pipes 14 from whence it passes radiallyoutwardly between the flanges 13 and plates 20, thence through thedrilled holes 24 into the grooves 23 and thence across the entiresurface of the roll to the opposite end thereof where it passes throughthe milled openings 25 into the space between the anges 13 and 17 andthence outwardly between the inner pipe 14 and outer pipe 22. lt will beapparent that alternate grooves 23 thus receive the chilled brine forpassage therethrough in opposite directions and that the shell 26 willthereupon be chilled substantially uniformly due to the fact that thealternate grooves 23 are acquiring heat from the shell 26 as they passtherebeneath. In a given example, it was found that there was anincrease of approximately 8 Fahrenheit in the brine temperature when itpassed from one end of the roll to the other in an optimum design. Sincealternate grooves are carrying such brine in opposite directions, itwill be readily apparent that the acquisition of heat from the shell 26into the brine will thus be more evenly distributed in the device as awhole. It will also be seen that since the grooves 23 extend at an angleother than perpendicular to the axis of the roll, and since the shell 26is relatively quite thin, that the nip or line of contact between theroll of the instant invention and a pressure roll or the like withwhichit may be used, may not ride a particular groove which would be the caseif the grooves extended axially. That this is of importance will beapparent from the fact that in the case of a device of the presentinvention wherein the roll is one hundred inches in length, such nipload is ordi narily twenty thousand pounds. It will also be apparentthat the angular relation of the grooves 23 as aforesaid, permitsgreater length of such grooves in a given roll thus permitting greaterdistribution of the heat-acquiring properties of the brine passingtherethrough.

While but one form of the invention has been shown and described herein,it will be readily apparent to those skilled in the art that many minormodifications may be made without departing from the spirit of theinvention or the scope of the appended claim.

What is claimed is:

A device of the character described comprising av drum having a firstseries of spaced helically extending grooves formed in the outer facethereof, said drum having a second series of like grooves eachpositioned between a pair of adjacent grooves of said lirst series ofgrooves, a shell aixed upon said drum, means for moving tiuids throughone series of grooves in one direction and through the other series ofgrooves in the opposite direction, means forming an inner chamberadjacent each end of said drum, means forming an outer chamber adjacenteach end of said drum, a supply pipe connected to each of said innerchambers, a discharge pipe connected to cach of said outer chambers,said drum having a radial hole extending from each alternate grooveadjacent one end thereof to communicate with one of said inner chambers,said drum having a like radial hole adjacent the opposite end of eachremaining groove to communicate with the other inner chamber, said drumhaving a plurality of passageways each formed in that end thereof remotefrom said radial holes and each interconnecting a groove with anadjacent outer chamber, said means forming said outer chamberscomprising a relatively large circular recess in cach end of said drum,and an annular flange aixed to said drum in each of said relativelylarge recesses, and said means forming said inner chambers comprising arelatively small recess formed in each end of said drum inwardly of andcommunicating with the relatively large recess of that end of the drum,and a 0 recesses, anges, cover plates and supply pipes being mutuallyconcentric.

References Cited in the tile of this patent UNITED STATES PATENTSv GreatBritain Sept. 17, 1913

